In your document (FCC19-123) you rightly highlight the great advantage of AM broadcasts, primarily the ability to cover large areas and number of listeners, while the band itself is losing popularity because of a variety of issues to do with propagation, interference, environmental changes. At the same time, digital audio broadcasting is no longer the new platform it was in 2002. At that time FCC mandated a proprietary system (IBOC, “HD radio”) as the only system to be used in the USA with the possibility of applying DRM for HF.

Since then DRM (the ITU recommended, only digital audio broadcasting for all bands, open standard, has been tested and used all over the world on all bands, short wave, medium wave and FM).

So while you are recommending now pure digital HD, based on the NAB tests and WWFD not completely convincing trial, we would urge the FCC to consider opening the straightjacket of 2002 and allow DRM to be used as a sure, tested, efficient way of digitizing the AM band.

There are several reasons for this:

DRM digital radio delivers in the AM bands significant benefits:

Audio quality that is on par or better than FM. DRM of all recognized digital
standards is the only one using the ultra-efficient and compressed xHE-AAC audio
codec that delivers at even very low bit-rates exceptional audio quality for speech
but music, as well. (https://www.drm.org/listen-compare/)

Auxiliary Data. DRM is the newest, most complete, open standard for digitizing radio in
all frequency bands, and is recommended by ITU. DRM has been devised as a direct
heir to analog AM (SW, MW). It uses 9/10, 18/20 kHz bandwidth and has a useful content
bit rate of up to 72kbps. It carries up to 3 programs on one frequency and one data channel, while data can be carried on each of the audio channels as well. One of the great advantages of DRM is that alongside excellent audio, the receiver screens will display visual information of any kind required (albums’ titles, singers’ photos, maps, visuals of any sort, data of any kind). The Journaline application allows for extra information from the internet or the RSS feeds of the broadcaster to be captured and displayed. Currently broadcasters like the BBC, All India Radio, KTWR in Guam are using this extra facility that clearly differentiates digital form analog as a superior option.

Power/energy efficiency. Using SW or MW in DRM can reduce the power used up
to 80%). As per calculations made by Ampegon, a medium wave transmitter can
cover an area of 235000 sq km with a 100kW transmitter. The DRM EPR of such a
transmitter is about 50kW and the coverage area is the same, while instead of one
analog programme up to three digital channels and one data channel can be
broadcast, all in excellent audio quality.

Spectrum efficiency (more programmes can be broadcast on one single frequency
used for one programme in analog) as explained above.

DRM, unlike analog, offers enhanced and stable audio quality that is FM-like
(mono or stereo). DRM also offers multiservice data enabled by applications like
Journaline (the enhanced text services, more information captured as RSS feeds or
form other internet source), slideshows, multilingual text (practically being able to
show any characters of any language not just Latin script), and the Emergency
Warning Functionality (EWF) in case of disasters.

Interference. This has not been noted as the DRM signal will always be lower than
the analog one. AIR has not noted any interference in its operation of DRM
transmitters. The mask values required for an optimal functioning of DRM
transmitters is clearly stipulated in the ITU documents and as long as the network
planning is correct, and the mask is respected there should not be any issue of
interference in digital-analog or digital-digital DRM transmissions.

Receivers. Currently there are several receiver models and SDR options for the
reception of DRM in AM. India has almost 2 million new cars fitted with DRM
receivers, at no cost to the buyers, that are capable of and are receiving DRM
mediumwave signals. The audio quality is excellent and a sure benefit to the users.

DRM is in direct succession to the analog AM (and FM) services, not owned or
controlled by any single company and immediately available with full know-how and
technology access by the transmitter and receiver industry.

As HD in mediumwave is a bit of a necessary step but still a leap in the dark, it
would make sense from the practical aspects and even receiver solution availability
to allow DRM as the best, clearly proven solution of digitizing the AM band (in
preference or alongside HD) in the US.

In short, the salient advantages of DRM are:

The audio quality offered by DRM is equally excellent on all the transmission bands:
MW, SW or VHF

Robust signal unaffected by noise, fading or other forms and interference in all bands

Clear and powerful sound quality with facility for stereo and 5.1 surround

More audio content and choice: Up to two and even three audio programmes and one
data channel on one frequency

Extra multimedia content: Digital radio listeners can get multimedia content
including audio, text, images and in future even small-scale video, such as:

Electronic Programme Guide (EPG), showing what’s up now and next; search
for programmes and schedule recordings

Slideshow Programme accompanying images and animation

Traffic information

Automatically switch for disaster & emergency warnings in case of impending
disasters in large areas, automatically presenting the audio message, while providing
detailed information on the screen in all relevant languages simultaneously. Great
potential to become the surest and widest means of alerting the population to
emergencies.

Therefore, we urge FCC to take a wide view and consider all options including DRM, if AM is worth futureproofing in the USA.

DRM’s a nice idea but that means another kind of receiver that people have to go out and buy just to get AM. There might be ways to upgrade car stereos depending on how new the car is, and I’m not a fan of IBOC, but at least it’s built in to a lot of modern car stereos and AM stations can run a blended analog/digital transition today so the overall cost to consumers is lower than adding in DRM at the consumer stream.

I’m also noticing AM IBOC implementations have been turned off in my area; we used to have two AM IBOC stations and we don’t have any. Are there other localities in the same situation?

Mike & Tom,
As you say the huge compromises used to make IBOC work has made it unpopular with broadcasters and listeners. Particularly the low power of the digital signal has meant that receivers will often blend back to analog if the errors at the receiver are high.

I live in a DAB+ country where there is no overlapping of broadcasts into adjacent channels and the radiated power is not limited by interference.

If the errors get too high the receiver mutes, however because of the greater digital power and the superior error correction and that all the digital carriers are unique where as in IBOC those above the carrier are a mirror image below the carrier the muting only really occurs near the edge of the analog coverage are for FM. which is commonly transmitted from the same tower.

DRM not only operates in the MF band but also operates with a higher data rate in the almost vacant TV channels 2 – 6 as well as the “FM” band where the signal bandwidth is half that of FM or a quarter that of IBOC in the FM band.

No body I can find will publicly say how many active HD radios are in use because I’ll bet that many of the radios manufactured in 2002 have died.

Lastly the digital processing in DRM and DAB+ are almost identical and are in widespread use in Europe and Asia, which leaves the USA/Mexico market the only ones using HD radio

Mangosman – I think for this discussion you have to completely focus on the North American market as it is today and forget what else is going on in the world. Same with Canada and Mexico because they tend to follow what we do in the USA.

I would say most people who can afford to do so are going into personally curated content over the internet whenever possible – Spotify, Apple Music, Amazon Music, and the like. If they can pay for the bandwidth and the subscriptions, they’re getting what they want to listen to. Bandwidth is cheap at the residence, so there hasn’t been that much demand for IBOC-enabled receivers.

Where IBOC lives is in the car market. I saw an article in Inside Radio from early 2019 mention there are over 2000 stations transmitting HDRadio, over 50 million IBOC radios in cars, and more than half of all cars sold in the USA now have HDRadio receivers. If those numbers are true, that’s definitely more than I would have thought. Mobile internet is still really expensive and limited to bandwidth capacity at the towers, and 5G implementations may change the game significantly – it’s too early to tell though.

Point being – If the numbers in Radio World are correct and I’m being pragmatic about the FCC and their perceived favoritism towards businesses and economics over technical arguments, IBOC is too entrenched at this point to consider a switch to DAB/DRM.

You cannot improve by keeping using 1900 technology. Who remembers Windows3.1!

If the FCC wants to convert to HD radio digital all the receivers have to be replaced as well.
So, if there is to be an upgrade then lets use the best system ie DRM.

Remember that in Norway they switched off FM and AM on all major networks and within a year the ratings on those networks had returned to their previous levels using DAB+. The incentive for listeners was many more programs.

DRM has an emergency warning system which will wake the radio and even sleeping listeners, tune to the emergency broadcast if you are in the affected area, show you maps of the emergency and a set of multilingual indexed detailed instructions on what to do, and lastly provide data to the GPS to get it to reroute the traffic around blocked roads.

You cannot get improvement without replace old technology. Remember Never Twice the Same Colour analog TV was replaced with digital TV. The receiver was replaced!

I don’t disagree with you completely mangosman but how many people do you think would replace the radio in their car to get DRM? The emergency alert function is a great idea but my $25 WX radio does the same thing.

I wish people would stop spreading the myth that digital is 80% more efficient — it doesn’t hold up to common usage. We saw this on HD Radio as the signal fell apart close to the tower, we see it in ATSC as VHF channels cut their power by 80% and the signal won’t reach 10 miles without issues, and we’ll see it with DRM if they tell 1kW AM stations they can cut to 200w and have the same coverage.

MW is still one of the best ways to get information out during an emergency like a hurricane or earthquake where there are power outages. If the US adopted DRM for MW every single receiver currently in use would be useless. I cannot imagine every car owner being willing to replace the radio in their vehicle. This reminds me a lot of the AM stereo debacle.

Please make a submission to https://www.fcc.gov/document/fcc-proposes-allow-all-digital-am-broadcasting so that the USA can have; a side by side comparison of DRM and HD radio test using a 50 kW AM transmitter which has been modified to switch from one system to the other. These transmitters are available in North America.
The tests should include objective characteristics such as; Electricity consumption Decoded data error rates at 1 km from the transmitter and at the edge of the designed coverage area for a 50 kW AM transmitter in AM mode.
The level of impulse interference required to either cause a drop out or a blending to AM.
the data rate capable of updating GPS systems in vehicles for emergency road conditions under hurricanes, snow storms and tornadoes….

Comparisons of;
sound quality on the main channel and when in multichannel mode of the additional channels using speech only as well as music including individual instruments of an orchestra image quality of any transmitted images in slide show or artistic experience the ability to show indexed multipage text messages Emergency Warning system to show radios being woken up, loudly announcing warnings, displaying text messages in multiple languages and this being limited to the target emergency area.

Please remember that HD radio is only adopted in the USA and Mexico. The rest of the digital world only uses DAB+ and DRM with only the UK using DAB.
Also every HD radio listener has to pay xperi for the technology either by the broadcaster or the receiver manufacturer in addition to patent rights for the equipment.
US citizens please make submissions to the FCC for a side by side trial. The FCC has made bad technical decisions in the past such as NTSC colour analog TV, ATSC digital TV and hopefully not HD radio.

A lawyer from the FCC had to tell me how to get to the express web page. I submitted my comments that I reject HD IBOC and asked them to scrap the current proposal and create a new one to pit head to head HD and DRM in a non-biased manner. IBOC sucks, plain and simple.

Affiliate links

Many of you have suggested in the past that the SWLing Post join an affiliate links program.

The SWLing Post now participates in two affiliate advertising programs with two large retailers that still sell shortwave radios, the Amazon Services LLC Associates Program and the eBay Partnership, designed to provide a means for sites like ours to earn advertising fees by advertising and linking to these retailers of radio products. Many of our links now function as affiliate links. This means that by clicking on these links, a small percentage of the purchase price for goods you purchase from these sellers will help support our site’s running costs. We hope you understand, and are grateful for your support.

But please note that we will never create a post and product link explicitly to receive a commission. Additionally, we always try to include links to other retail options if they are available, as we support and freely advertise independent ham radio retailers. Thank you, too, for your support of these sites.